On round nose Minis the drain channel rubber was part HYA3925 (38.75" long, expanded neoprene rubber, .59" x .32"), then for the Clubman became part HYB3743, replaced by part HYA4688 (same dimensions but 43.25" long). So a few changes for such a simple part that was to reduce vibration of the bonnet.
Interestingly, in August 1971 shortly after the Clubman was introduced the full length rubber was replaced by two shorter lengths at the extremities of the drain channel. I assume this was because the full length rubber would allow water to accumulate causing premature rusting of the channel, but I don't have anything to substantiate that view.
See para 6 of the Service Liaison Letter below.
